Simulation of Combustion in Porous Media With a Two-Energy Equation Model

2011 ◽  
Author(s):  
Marcelo J. S. deLemos ◽  
Jose´ E. A. Coutinho
Keyword(s):  
Porous Media ◽  
Flame Front ◽  
Control Volume ◽  
Numerical Technique ◽  
Simple Algorithm ◽  
Equation Model ◽  
Gas Temperature ◽  
Inlet Velocity ◽  
Excess Air ◽  
Porous Burner

This work presents numerical results for two-dimensional combustion of an air/methane mixture in inert porous media using turbulence and radiation models. Distinct energy equations are considered for the porous burner and for the fuel in it. Inlet velocity and excess air-to-fuel ratio are varied in order to analyze their effects on temperature and flame front location. The macroscopic equations for mass, momentum and energy are obtained based on the volume average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. Results indicate that for high excess air values, the gas temperature peaks are reduced. Also, for the same conditions the flame front moves towards the exit of the burner. Results also indicate that the same flame front behavior occurs as the inlet velocity increases.

Laminar Heat Transfer on a Wall Covered With a Layer of Porous Material Simulated With a Two-Energy Equation Model

2010 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Felipe T. Do´rea
Keyword(s):  
Porous Material ◽  
Control Volume ◽  
Numerical Technique ◽  
Simple Algorithm ◽  
Porous Matrix ◽  
Equation Model ◽  
Energy Model ◽  
Governing Equations ◽  
Volume Method ◽  
Macroscopic Equations

This paper presents simulations for a jet impinging against a flat plane covered with a layer of a porous material. Macroscopic equations for mass, momentum and energy, for the fluid and for the porous matrix, are obtained based on the volume-average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. The effect of porosity and energy model on the local distribution of Nu was analyzed. Results indicate that for low porosity materials, a substantially different Nu number is calculated depending on the energy model applied.

Turbulent Impinging Jets Into Permeable Media

2006 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Daniel R. Graminho
Keyword(s):  
Control Volume ◽  
Numerical Technique ◽  
Flow Distribution ◽  
Simple Algorithm ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Impinging Jets ◽  
Porous Substrate ◽  
Transfer Coefficients ◽  
Permeable Media

Impinging jets are widely used in industry to modify local heat transfer coefficients. The addition of a porous substrate covering the surface contributes to better flow distribution, which favors many engineering applications. Motivated by that, this work shows numerical results for a turbulent jet impinging against a cylindrical enclosure with a porous substrate at the bottom. Macroscopic time-averaged equations for mass and momentum are obtained based on a concept called double decomposition, which considers spatial deviations and temporal fluctuations of flow properties. The numerical technique employed for discretizing the governing equations is the control volume method in conjunction with a boundary-fitted coordinate system. The SIMPLE algorithm is used to handle the pressure-velocity coupling. The influence of the cylinder height on the mean and statistical flow fields within the entire cavity is presented.

The Effect of Radiation and Turbulence on Heat Transport in Combustion in Porous Media

2007 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Porous Media ◽  
High Efficiency ◽  
Reaction Rates ◽  
Equation Model ◽  
Test Case ◽  
Process Industries ◽  
Porous Burner ◽  
Reliable Temperature ◽  
Double Decomposition ◽  
Flow Variables

Combustion in inert porous media has been extensively investigated due to the many engineering applications and demand for developing high efficiency power production devices. The growing use of efficient radiant burners can be encountered in the power and process industries and, as such, proper mathematical models of flow, heat and mass transfer in porous media under combustion can benefit the development of such engineering equipment. This paper proposes a new mathematical model for computing temperature and flow variables inside a porous burner. A new concept called “double-decomposition” is used to represent all transported variables. A set of governing equations is presented and the numerical solution method proposed is discussed. Computations are carried out for a test case considering a simple one-energy equation model and one-step reaction rates. Simulations are presented comparing the inclusion of turbulence and radiation transfer in the model. It is shown that for high Re flows, inclusion of turbulence is as important as modeling radiation for obtaining reliable temperature distribution within the porous material.

Numerical Simulation of Laminar Confined Impinging Jet in a Composite Channel

2008 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Porous Layer ◽  
Control Volume ◽  
Numerical Technique ◽  
Simple Algorithm ◽  
Local Distribution ◽  
Governing Equations ◽  
Stagnation Region ◽  
Volume Method ◽  
Material Porosity ◽  
Macroscopic Equations

This work shows numerical results for a jet impinging onto a flat plane covered with a layer of a porous material. Porosity of the porous layer is varied in order to analyze its effect on the local distribution of Nu. Macroscopic equations for mass and momentum ae obtained based on the volume-average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. Results indicate that inclusion of a porous layer decreases the peak in Nu avoiding excessive heating or cooling near the stagnation region.

Effect of Porous Insert on Heat Transfer in a Backward-Facing Step Flow

2016 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Wagner C. Galuppo
Keyword(s):  
Heat Transfer ◽  
Porous Materials ◽  
Control Volume ◽  
Numerical Technique ◽  
Heated Surface ◽  
Simple Algorithm ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Backward Facing Step ◽  
Porous Insert

We present numerical results for turbulent heat transfer past a backward-facing-step channel with a porous insert. A non-linear eddy viscosity model was applied to handle turbulence. For a constant Darcy number, the thickness of the porous insert was varied in order to analyze its effects on the flow pattern, particularly the damping of the recirculating bubble past the insert. Further, the reduction of the Nusselt number along the bottom heated surface, when using porous materials inside the channel, was investigated. The numerical technique employed for discretizing the governing equations was the control-volume method. The SIMPLE algorithm was used to correct the pressure field and the classical wall function approach was utilized in order to handle flow calculations near the wall. Comparisons of results simulated with different porous materials were presented.

Turbulent Impinging Jet Into a Rigid Porous Layer

2011 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Porous Layer ◽  
Control Volume ◽  
Numerical Technique ◽  
Simple Algorithm ◽  
Stagnation Region ◽  
Thermally Conducting ◽  
Energy Equations ◽  
Volume Method ◽  
Highly Porous ◽  
Macroscopic Equations

This work shows simulations for a turbulent jet impinging against a flat plane covered with a layer of permeable and thermally conducting material. Distinct energy equations are considered for the porous layer attached to the wall and for the fluid that impinges on it. Parameters such as Reynolds number, porosity, permeability, thickness and thermal conductivity of the porous layer are varied in order to analyze their effects on the local distribution of Nu. The macroscopic equations for mass, momentum and energy are obtained based on volume-average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. Results indicate that inclusion of a porous layer eliminates the peak in Nu at the stagnation region. For highly porous and highly permeable material, simulations indicate that the integral heat flux from the wall is enhanced when a thermally conducting porous material is attached to the wall.

Turbulent Impinging Jet Into a Confined Porous Layer

2005 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Daniel R. Graminho
Keyword(s):  
Porous Layer ◽  
Control Volume ◽  
Numerical Technique ◽  
Flow Distribution ◽  
Simple Algorithm ◽  
Local Heat Transfer ◽  
Impinging Jet ◽  
Local Heat ◽  
Impinging Jets ◽  
Transfer Coefficients

Turbulent impinging jets on heated surfaces are widely used in industry to modify local heat transfer coefficients. The addition of a porous substrate covering the surface contributes to a better flow distribution, which favors many engineering applications. Motivated by this, the present work shows numerical results for a turbulent impinging jet against a cylindrical enclosure with and without a porous layer at the bottom. The macroscopic time-averaged equations for mass, momentum and energy are obtained based on a concept called double decomposition, which considers spatial deviations and temporal fluctuations of flow properties. The numerical technique employed for discretizing the governing equations is the control volume method in conjunction with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm is used to handle the pressure-velocity coupling. The influence of characteristics of the porous layer on the mean and statistical flow fields within the cylinder is presented.

Turbulent Flow and Heat Transfer in a Porous Chamber

2003 ◽  
Author(s):  
Marcelo Assato ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Turbulent Flow ◽  
Control Volume ◽  
Numerical Technique ◽  
Turbulence Models ◽  
Simple Algorithm ◽  
Macroscopic Models ◽  
Flow And Heat Transfer ◽  
Non Linear ◽  
Porosity And Permeability ◽  
Volume Method

This work presents a numerical investigation of turbulent flow past a porous structure in a channel using linear and non-linear eddy viscosity macroscopic models. Parameters such as porosity and permeability of the porous material are varied in order to analyze their effects on the flow pattern, particularly on the damping of the recirculating bubble after the entrance and exit regions. The numerical technique employed for discretizing the governing equations is the control-volume method. The SIMPLE algorithm is used to correct the pressure field. The classical wall function is utilized in order to handle flow calculation near the wall. A discussion on the use of this technique for simulating the flow in question is presented. Comparisons of results simulated with both linear and non-linear turbulence models are shown.

Simulation of Axial Flow in a Bare Rod Bundle Using a Non-Linear Turbulence Model With High and Low Reynolds Approximations

2002 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Marcelo Assato
Keyword(s):  
Control Volume ◽  
Numerical Technique ◽  
Axial Flow ◽  
Simple Algorithm ◽  
Eddy Viscosity Model ◽  
Rod Bundle ◽  
Non Linear ◽  
Fully Developed Turbulent Flow ◽  
Low Reynolds ◽  
Volume Method

This work presents a numerical investigation of fully developed turbulent flow in a triangular sub-channel of a bare rod bundle using a Non-Linear Eddy Viscosity Model (NLEVM). The numerical technique employed for discretizing the governing equations is the control-volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to correct the pressure field. The classical wall function and a low Reynolds model were used in order to handle flow calculations near the wall. In this work, the influence of constants of calibration existing in the non-linear terms of the model is analyzed.

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